What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

RV-as-glider fastasy tried

randylervold

randylervold

moderator
(Long post made for entertainment value only, move on if you're looking for a tech tip or empirical data, this isn't it.)

I'm sure most of you know the experience of winter daydreaming about RV flights you're going to take once the weather improves, right? Well, today on a whim I realized one of the recurring fastasies I've had for several years now. It involves trying something a bit weird with an RV so I thought a few of you might find this interesting....

Here's the fantasy: take a day with nothing else to do, fly east up the Columbia River gorge from my home airport (VUO) to the Hood River Airport (4S2), and try to do some ridge soaring in my RV. Sounds nuts but let me explain. I've flown gliders off and on since '92 and even owned a sailpane for a while. I LOVE soaring, but RVs are just a more accessable and practical form of aviation so I'm inactive in soaring now. Hood River is a neat local soaring area that has a ridge to East with a prevailing west wind. The ridge is about three miles from the airport so the standard procedure is to take a tow in a your glider from the airport and release near the ridge. Some days you can fly the ridge lift all day, and on others you can work the ridge to climb up the NE side of Mt.Hood and if you're lucky, and the high altitude wave is cooking, you can get up into it and do some serious wave soaring. There's even an ATC "wave window" that can be opened to keep you clear of the airliner traffic while you're surfing the wave at 20k', but I digress.

My recurring fantasy is to take my RV up to the ridge, set the power for neutral lift, and see if I can stay aloft in the ridge lift by just flying around back and forth like you would in a glider. This morning I was returning from breakfast in Bend, Oregon and happenend to fly right over the Hood River area. I had nothing pressing to do so I dropped down to check the ridge. Sure enough, my EFIS told me there was about a 20 mph West wind blowing. Perfect, let's give this a try! I slowed down and set power to 10" of MAP and 1900 rpm. Just by feel this seemed to be a setting that in no wind would allow me to just barely maintain altitude at a best-glide speed. I set about 10 degrees of flaps and started across the ridge face at 90-100 mph (my RV-3B tail really starts sagging at speeds below about 105 without that 10 degrees of flaps). My VSI is way to slow to function as a variometer like you'd have in a glider so I just used seat of the pants feel to tell when I was climbing or not. As I started across the ridge face I could see myself climbing, cool! I flew close to the ridge imitating a glider and felt more lift in some areas then others and confirmed that the VSI was hopelessly behind. Then, just as in real ridge soaring, I turned away from the ridge to reverse course and fly back up the ridge face. Whoa, huge sink during the turn! Those long skinny high aspect ratio glider wings turn without bleeding off much airspeed or altitude at all. NOT so with the short fat RV wings. So I lost a bunch of altitude on the turn and tucked back into the ridge to try to gain it back. By working very close to the ridge I managed to gett back a little but not all of it and had to add just a bit of power to go along with the lift to get back up the ridge face. After two or three more attempts at turning I found I could work the ridge to gain or maintain lift, but the turnaround really screwed things up.

Having soared this ridge in my glider I was able to compare the experience. As sensitive as my RV-3 is on the stick (most who have flown RV-3s say it is considerably more sensitive than a normal-sized RV), it is does not provide nearly the "feel" that a glider does.

Darn, I was hoping this would be a fun thing to do, turns out it's really not that neat. Oh well, at least I finally got to try it. Now I'll have to dream up a new RV flight fantasy for this winter. :)

There are some great places along the West coast where the ocean wind hits ridges on the coast and you can soar all day. One of you West coast RVers should try this and see how you do, maybe we can compare notes on technique.
 
Last edited:
Cool!

That sounds really cool Randy - I'd love to give that same thing a try....unofrtuantely, we have a distinct lack of ridges down here on the gulf coast. Perhaps if I fly really close to a Level 5 thunderstorm and get into the updraft....:eek:;)

I've thought that a great "retirement stable" in the hangar would include a motor glider, just for spending lots of time in the air. I'm hoping that in twenty years, there'll be an efficient electric Motor Glider that we can fly for next to nothing.....
 
Randy,

Try wave soaring in your RV sometime, you'll find it works much better.

One night my glider instructor and I spent about an hour and a half parked at 12,000' or so in the California City wave in a Cessna 170, just sitting there shooting the bull and taking in the view of the city lights...with the engine shut down!

We almost killed the battery with the nav lights...
 
Ridge Soaring

"Back in the old days", I used to ridge soar my Aeronca 7AC on the North Shore of Oahu, Hawaii on the ridges adjacent to Dilingham Air Field. Didn't shut the engine down, (65hp--no starter), but could stay up as long as I wanted on a normal Trade Wind day. Ahhh---the memories!!!!!!!!!!!:D
 
Great Story

Hey Randy,

That would have been cool if had worked. Last Fall, I was flying my 7 over the desert and had it set up for 90 kts, a 2500 ft. (working on IFR approach speeds). Suddenly the nose pitched up and the VSI went to 1000 fpm. I pulled the power and added just short of half flaps. Began a shallow left turn and worked on centering the lift. Soon, the power off 7 was climbing at 600 fpm, trimmed for 80kias. Rode that up to 5800 ft, just short of the 6000 base of the Phx Class B.

They can be thermalled if it is strong enough.
 
Last edited by a moderator:
Ironflight said:
That sounds really cool Randy - I'd love to give that same thing a try....unofrtuantely, we have a distinct lack of ridges down here on the gulf coast. Perhaps if I fly really close to a Level 5 thunderstorm and get into the updraft....:eek:;)

I've thought that a great "retirement stable" in the hangar would include a motor glider, just for spending lots of time in the air. I'm hoping that in twenty years, there'll be an efficient electric Motor Glider that we can fly for next to nothing.....
Click to expand...

http://www.windward-performance.com/news.php

this guy thinks there will be a battey powered electric glider within a year, hopefully less. the way batteries develop he thinks there may be a 600mile range setup within 6-8 years.
 
Yes, but can you do a competition finish, coming over the line at 120kt and 50 agl, water spraying, and then make a normal pattern? :D We had a contest at TSA (Texas Soaring Assoc, not the airport "security" people) yesterday, and there were some very nice finishes.

(Stock photo for those who haven't seen a competition finish before)

LS40075.jpg


The rest of us can just watch really good soaring pilots having fun.

TODR
 
Last edited:
You better believe it.

The "Whoa, huge sink during the turn!" was what I was trying to impress in the "turn-back" thread. Some pilots don't believe that initial sink happens.
 
Alex Caldwell said:
I set about 10 degrees of flaps and started across the ridge face at 90-100 mph

I did some rough tests a couple of years ago with my RV-3 using a GPS glide
computer program called "Soaring Pilot" that runs on a PDA, and got these
numbers. I've not tried soaring the RV-3, but it would appear that you'd need
to go slower than 90-100 to get your minimum sink rate down to where you
could soar in all but the most powerful (and fairly rare) types of soaring
conditions. I don't think I'd necessarily want to fly that slow down low on a
ridge on a turbulent day, so I'm not advocating going out and trying it either.

I got a slightly worse sink rate with one notch of flaps than no
flaps. Even if you can't soar, you can still extract quite a bit of energy from
an airmass that is full of thermals when cruising by zooming up and slowing down in lift,
and diving moderately and speeding up in sink, which is what the sailplanes
do. ATC may not like it if you are on flight following or IFR, however! :)


Empty weight 805 lbs. Pilot 150lbs Fuel 15 gal.
Fixed pitch wood prop. Engine running, throttle at idle.

Speed mph ---- Flap Setting ---- Sink Rate fpm
110 ------------- 0 ------------- 1160
100 ------------- 0 ------------- 858
90 ------------- 0 ------------- 686
80 ------------- 0 ------------- 679
75 ------------ +1 ------------- 673
70 ------------- 0 ------------- 576
Click to expand...

Good info Alex, you spent much more time on it than I did. You're right though, even though you measured minimum sink down at 70 mph I don't think I'd want to fly an RV that slow, especially right down on a ridge. Also, unlike a glider, RV handling at that speed isn't especially crisp. I'm surprised that a little bit of flaps didn't help reduce sink. At 70-80 mph without flaps my RV-3 tail sags really bad, doesn't yours?

So I take it from all the comments I'm not the only who's given this a try, cool!!
 
Vans

I think we should write Van and tell him to get back into the garage.
Wasn't he working on a motor glider? Something we could afford and BUILD.
 
You must log in or register to reply here.
Back
Top